The present invention relates to tracking the position of a writing instrument, and more specifically, to calibrating a system that tracks the position of writing instrument.
In the prior art, a number of input devices exist that allow a user to provide input to a computer or similar device. Typically, these input devices (i.e., a mouse, a touch sensitive screen or pad) are physically connected to the computer and do not allow a user to simply write the input as he or she would with a writing instrument such as a pen or a pencil. For some activities, such as sending a facsimile (faxing) or making an entry in an appointment book, it would be simpler for a user to write out a message or entry as he or she would with a writing instrument that is not physically connected to the computer rather than use prior art input devices to create a message for faxing or to enter an appointment.
In order to provide the user with a writing instrument as an input device, a system for tracking position(s) of a writing instrument must be provided. This system monitors movements of the writing instrument and converts these movements into a representation of the user input. The better the tracking system, the more accurately the user input is received. However, because the writing instrument may be used in many different environments where conditions such as altitude and temperature vary, the tracking system to track the position of the writing instrument may not perform accurately, resulting in the receipt of incorrect input. Therefore, it is desirable to calibrate the writing instrument for the environment in which the writing instrument is used.
A method and apparatus for calibrating a system that tracks the position of a writing instrument is disclosed. Multiple sensors generate outputs based on a position of the writing instrument. Sensor readings are obtained for multiple predefined positions of the writing instrument. A mapping of sensor outputs to writing instrument positions is generated based on the sensor readings at the predefined positions.